Hydrology-mediated ecological function of a large wetland threatened by an invasive predator

• Published in: The Science of the total environment 2023-01, Vol.857, p.159245-159245, Article 159245
• Main Authors: Pintar, Matthew R., Dorn, Nathan J., Kline, Jeffrey L., Trexler, Joel C.
• Format: Article
• Language: English
• Subjects: Ecosystem restoration; Invasive species; Non-native species; Population declines; Swamp eel; Top-down effects
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2022.159245

Invasive species are one of the greatest threats to ecosystems, disrupting ecosystem function and leading to the collapse and extinction of native species. While populations of native fishes in the Everglades are tied to the system's natural hydrological dynamics, Asian Swamp Eels (Monopterus albus/javanensis) are drought-resistant fish first reported from Florida in 1997 and the Everglades in 2007. Using a 26-year dataset that included a 13-year baseline period prior to swamp eel arrival in Taylor Slough, we assessed population changes of common small fishes and decapods that are important prey for larger vertebrate predators. After invasion, populations of two crayfishes collapsed by >95 %, two fishes declined by >80 %, two fishes had intermediate declines of 44–66 %, and three species remained unchanged. Species most strongly reduced were those dependent on predator-free habitats at the onset of the wet season, indicating drought-resistant swamp eels have introduced novel predator effects and disrupted the hydrology-mediated production of aquatic animals that are prey for many larger predators. Ongoing Everglades restoration is designed to restore hydrological conditions that support production of crayfishes and fishes, and nesting wading birds reliant on them. Water management may have facilitated the invasion of swamp eels. Our results suggest that the continued spread of swamp eels may result in adverse consequences for Everglades trophic dynamics and potentially diminish benefits expected from the $20B+ restoration. [Display omitted] •Asian swamp eels have spread into Everglades marshes since 2010.•Populations of native crayfish and small fish collapsed after invasion.•Drought-resistant traits of swamp eels undermined natural environmental dynamics.•Water management may have played a role in swamp eel spread.•Everglades restoration and trophic dynamics may be threatened by this invasion.